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N-Fix - too good to be true?

November 2013

CC photo by Wheat initiative on Flickr

The holy grail of gene technology has long
been the creation of plants which can fix nitrogen from the air to provide
their own nitrogen fertiliser.Scientific and financial resources have been poured into attempts to
develop such GM crops in Britain.

There's no doubt that world agriculture
desperately needs to find an alternative to our current dependenceon artificial nitrogen fertilizers.They’re expensive, energy- and fossil fuel-hungry,
climate-, environment- and health-damaging.

Natural conversion of nitrogen gas in the
air to a form usable by plants is carried out by soil bacteria.Scientists who are aware of the complexity of
nitrogen-fixation in such bacteria have reservations about whether the process
can be translated by GM into higher plants.Besides the 20 genes involved (each structured to express in bacteria
not in plant cells) and the enzymes needed (some of which are assembled from
separately generated components and some of which incorporate iron and
molybdenum ions), the reaction itself can only take place if oxygen is
excluded.The energy costs and metabolic
contortions needed to achieve such novel reactions and conditions in a plant
are so extensive that achieving a robustcrop at the end of the day may
be a “pipe-dream” (Institute of Science in Society).

However, researchers at Newcastle
University have been following another line of inquiry.They've come up with 'N-fix' technology.

According to the press release, N-fix is “a
natural, nitrogen seed coating” which is “environmentally friendly and can be
applied to all crops”.It involves
“neither genetic modification nor bio-engineering” but uses “naturally occurring
nitrogen-fixing bacteria”.N-fix is
based on a bacterium found originally in sugar-cane, which can be induced to
insert into plant cells: it potentially provides every cell in the plant with
the ability to fix nitrogen from the air.

This latest fertiliser-generating
technology has passed through preliminary tests in the laboratory and
glass-house.The next stages will be
field trials “to produce robust efficacy data”, and then regulatory
approval.It is anticipated that N-fix
crop plants will be commercially available within the next 2-3 years.

N-fix certainly seems to tick all the
boxes: a natural bacterium doing its natural thing inside conventional plants,
involving nothing more than a natural coating on the seed.

A paper published in 2006 describing a technique to induce nitrogen-fixing bacteria to colonise the inside of root cells in experimental model plants.

A patent dated 2008 for the technique described in the 2006 paper

A very recent power-point presented by 'Azotic Technologies' (the N-fix license-holding company), to promote the technology, although the information given is unreferenced and unpublished.

Beyond that, the only description available
is what’s contained in the Newcastle University press release.The media coverage of the announcement was
wide, but the release specified that no additional resources were available,
and requests for more information went unanswered.

Thus, the story so far seems to be:

A technique was invented for enabling the
invasion of plant cells by a microbe.This was quickly patented, after which no information entered the public
domain and no further quality control by peer review was applied to the
science.Two hundred species of novel
microbe-harboring crops are currently being prepared for
commercialisation.N-fix is going to
solve all the problems arising from the use of artificial nitrogen
fertiliser, feed people in poor areas, and will be on our dinner plates in a
couple of years.

The missing box is, of course, safety
testing.

N-fix is being pushed as so natural
that the question of safety just doesn't arise.(COMMENTIf your memories
of the GM issue go back to the 1990s, you'll be getting a feeling of déjà vu.)

What sort of safety questions does N-fix
raise?

Natural infection of sugar-cane by natural
N-fix bacteria follows physical damage to the root.The bugs lodge in the walls of root cells and
are transported into other parts of the plant in the xylem (water transport
channels).They are, therefore,
naturally limited to sites outside
the living cells.

Note.In natural nitrogen-fixing legumes such as
clover and peas, the bacteria dwell in protective nodules formed by the root:
the microbes are in very close proximity to, but not inside, the root cells to
which they supply nitrogen.

Azotic's 'natural' N-fix bacteria contained
in its 'natural' seed coating, seem to manage to get into the plant without
physical damage.Once inside, Azotic's
N-fix are able to breach the cell wall, enter the cell itself, and proceed to multiply
and spread throughout the plant inside the plant's cells.This seems to have no natural
parallel.

Thus, N-fix bacteria appear to have all the
infectious qualities of the perfect pathogen and, indeed, they are known to
cause plant disease when present at high levels, because they produce plant
growth hormones. At low levels of infection the extra hormone can boost growth,
but at high levels the plants are over-stimulated and become sickly.

Pictures of Azotic's N-fix in the 2006
paper show plant roots cells chock-a-block with bacterial colonies.Why aren't the plants succumbing to high
plant hormone levels?Perhaps the
'natural' N-fix bacteria in the 'natural' artificial seed coating aren't so
natural after all?

According to the 2006 paper, the mechanism
for N-fix bacteria penetration through the cell membrane is by sucrose-induced
'endocytosis' (i.e. the cell 'swallows' the bugs by enfolding them in a membrane).Sucrose-induced endocytosis is a natural
mechanism by which plant cells rapidly take in sucrose from their
surrounding.It's clearly not
natural for bacteria to sneak in by this route.

Endocytosis of the N-fix bugs was found to
happen only when the plants were inoculated with isolated bacteria.This suggests that, once inside the plant
cells, the rate of reproduction must be ferocious to fill up the root tissues
as they were seen to do.The possibility
of rapid evolution to another, possibly pathogenic, variety under these
circumstances is very real, and the transmission ofN-fix bacteria by sap-sucking insects is
already known to occur.

There are several other safety alarm bells
ringing for N-fix.Breaching of the cell
wall seems to involve hijacking the plant's own cell-softening agents,
'expansins'.Expansins are implicated in
the allergenic potential of pollen grains.Neither N-fix nor the protective mucoid coating it produces to block out
oxygen have ever been a meaningful part of our diet.The unprecedented quantities of N-fix
bacteria inside the plant cells using up plant nutrients and generating their own
by-products will affect the nutritional quality of the plant and will reduce
the root exudates which are a vital part of soil health. Moreover, the plants' metabolism and immune
responses will alter significantly in response to the presence of the invading
bacteria.

The Institute of Science in Society points
out that plants growing in healthy, chemical-free, organic soils are not
limited by nitrogen availability: numerous free-living and symbiotic natural
nitrogen-fixing microbes exist in organically-managed soils.

Interestingly, there is a lesson from the
far past on the dangers of artificial introduction of nitrogen-fixing bacteria
into the cells of a higher organism.In
the 1970s, scientists on much the same track as N-fix but with less
sophisticate resources at their disposal succeeded in introducing
nitrogen-fixing bacteria into soil fungi which live in close association with
pine tree roots.The idea was to boost
tree growth by supplying extra nitrogen direct to the roots.When applied to pine trees, the concept
worked to a degree.However, in the case
of one strain of fungus, the nitrogen-fixing modification made it pathogenic
and it penetrated to all parts of the plant, and killed it.Fortunately, this aberrant fungus never got
our of the laboratory, or it could have destroyed whole forests.

OUR COMMENT

Is the novel insertion of whole bacteria
inside plant cells just an extreme form of GM?Plant-bacteria hybrids clearly pose a risk to your health, your food
supply and the environment.All
safety-testing is being sidestepped.

Get ready to demand full environmental
stress trials which test both crop and microbe outcomes, and full life-long
animal feeding trials followed by clinical trials before any N-fix technology
comes anywhere near your dinner plate.

Also there is just too much secrecy
surrounding N-fix: demand transparency.

SOURCES

Nitrogen-fixing for All Crops Not the Answer, Institute of Science in Society Report, 23.09.13

World changing technology enables crops to take nitrogen from the air,Nottingham University Press Release, 25.07.13

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